Heh. Getting closer. It's not the Yamanote JR 
line, but it's one stop off that (I don't 
remember which line it is, but you can get there 
via Shinjuku).It's an excellent place to shop, as 
it's chock full of Mandarake stores. Though they 
seem to have cut their in-store availability of 
cels way back from what I remember them having 
before. Their Shibuya branch has a bit more.

Ikebukuro is also a good placed to shop. A couple 
of blocks down from Sunshine City is the main 
Animate store, a K Books used goods store and 
another used goods store squeezed in between 
them. There's also a Gamers and another anime 
store whose name escapes me there.

Akihabara is also good. More Animate, Yellow 
Submarine and some various other places.AWS used 
to be there. Not sure if they still are. Alas, 
the 8 story flagship Gamers store isn't there any 
more.

If you're into used manga/videotapes, Book Off in 
Harajuku is perfect. Cross the street from the 
main entrance to the train station and turn left. 
Go down 2-3 blocks until you find an alley 
teeming with young folk. Turn right and follow 
the "alley" to the end, turn right and Book Off 
is down about a block. Tons of CDs, Games, 
Videotapes, Manga.